PSA the median GPA is lower than it appears
Just a reminder that the median GPA is lower than it appears. So if you are stressed out about getting an A- or B+ you are ahead of the curve. Especially in STEM.
An advisor told me the STEM average is around a 3.2 at graduation (not counting the students who change majors) in humanities it is around a 3.5.
Remember the classmates who have better grades are more likely to share and those who do well in "hard" classes might not have structural limitations in their success(Not negating any hard work they have done.)(i.e. not having to work, prep school experience, not having mental health challenges.)
So you are probably doing a lot better than it feels. Remember you are in the top 99th percentile of students solely by being at Columbia.
(Also dropping and withdrawing is so common and even encouraged. I wonder what the average would look like if that weren't allowed.)